Sulfotransferase discussion

Potentially, individuals with low activities of the enzymes phenol sulfotransferase and glucuronyl-transferase may be more susceptible to phenol toxicity. Persons with ulcerative colitis may have an impaired capacity to sulfate phenol (Ramakrishna et al. 1991), which may increase the amount of unchanged phenol that is absorbed following oral exposure. Neonates may also be more susceptible to toxicity from dermally-applied phenol because of increased skin permeability and proportionately greater surface area. A study in which 10-day-old rats were more sensitive to lethality following oral exposure to phenol than 5-week-old or adult rats (Deichmann and Witherup 1944) further suggests that the young may be more sensitive to phenol. (For a more detailed discussion please see Section 2.6.) Because phenol is a vesicant, individuals with sensitive skin or pulmonary incapacity may be more sensitive to phenol. Individuals with kidney or liver diseases that impair metabolism or excretion of phenol and phenol metabolites may be more susceptible to phenol. 

A-Hydroxylation has been correlated with ultimate DNA adduct formation, and initiation of chemical mutagenesis in the reverse mutation assay89,90. Further support derives from esterification by acetyltransferases and sulfotransferases, which facilitates binding with DNA and mutagenesis. As discussed earlier, initial activation, the oxidative A-hydroxylation, occurs through metabolic conversion initiated mainly by microsomal CYP1A291,92. 

A cytosolic sulfotransferase has been identified in rat liver and kidney which utilizes 3 -phosphoadenosine-5 -phosphosulfate (PAPS) and shows a greater rate of sulfation for glycolithocholate than lithocholate. In an assay with the enzyme preparation, PAPS, and conjugated bile acids, 3 unidentified products were formed from taurocholate suggesting multiple sulfation of more polar conjugated bile acids [64]. The enzyme from liver, proximal intestine or adrenals of hamster produced only glycochenodeoxycholate 7-sulfate. Comparable results with the enzyme from kidney will be discussed in Section VI.3. Hepatic enzyme from the female hamster shows 4-fold greater activity than that of the male [65]. 

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